Correlates of femoral artery flow mediated dilation in a multi-ethnic sample of 12- to 26-year-olds

Objective: Endothelial dysfunction is one of the earliest events in the pathogenesis of cardiovascular disease (CVD). Studies involving healthy adults have found endothelial function, measured via flow mediated dilation (FMD), to be impaired in African Americans (AAs) compared to European Americans (EAs). The purpose of this study was to determine whether ethnic differences exist in FMD in a group of healthy teenagers and young adults, and to examine separately, by ethnic group, the relationships between FMD and several measures of adverse cardiovascular prognoses. Design: Subjects underwent measurement of various anthropometric, hemodynamic, and echocardiographic variables. Setting: Measurements were made in a laboratory setting. Participants: Subjects were 159 12- to 26-year-old AAs and EAs. Main Outcome Measures: FMD, endothelin-1 (ET-1) levels, at rest and in response to stress, and measures of cardiac structure and function. Results: Ethnic differences were not observed in FMD. Only pre-occlusion arterial diameter was significantly related to FMD in EAs (P<.001); whereas, among AAs, FMD was negatively correlated (all Ps<.03) with gender, pre-occlusion arterial diameter, relative wall thickness (RWT), resting plasma ET-1, and ET-1 increases, related to a behavioral stressor. Multiple linear regressions for AAs revealed that gender and RWT each explained a unique variation in FMD (Total model R² = .36, P<.0001). Conclusion: Ethnic differences in FMD are not in evidence for subjects in this age range. The inverse relationships observed in AAs between FMD and measures of altered endothelial system function, and ventricular structure and function, provide additional evidence for early clustering of measures of adverse cardiovascular prognoses in this group.